Filters for tobacco smoke

ABSTRACT

The specification discloses a filter for tobacco smoke which includes a basic substance, such as calcium hydroxide, which is capable of reacting with acid gases present in the tobacco smoke to remove certain of the undesirable impurities in the tobacco smoke, and to provide in the filter water through which the tobacco smoke is drawn to cool it and to remove particulate matters which otherwise would be carried by the tobacco smoke into the body of the smoker.

United States Patent Soussa et al.

FILTERS FOR TOBACCO SMOKE Inventors: Elie Michel Soussa; Jabbour Habayeb,

both of Amman, Jordan Lemo Limited, Grand Cayman, British W. indies Filed: Feb. 24, 1971 Appl. No.: 100,736

Assignee:

Related US. Application Data Continuation of Ser. No. 768,210, Oct. 8, 1968, abandoned.

U.S.Cl ..l31/10.9, 131/173, 131/265, 131/267 Int. Cl. ..A24b 15/02, A24d 01/06, A241 13/06 Field ofSearch ..131/261,265, 10, 10.7, 207, 131/109 References Cited UNITED STATES PATENTS Kosinski 131/265 [4 June 13, 1972 2,181,614 11/1939 Striefling ..131/10.9

FOREIGN PATENTS OR APPLlCATlONS 642,249 6/1962 Canada ..l31/17 R 685,822 1 1953 Great Britain 75 3,203 7/ 1956 Great Britain Primary Examiner-Samuel Koren Assistant Examiner-G. M. Yahwak Attorney-Bacon & Thomas [5 7] ABSTRACT 3 Claims, No Drawings FILTERS FOR TOBACCO SMOKE This application is a continuation of application Ser. No. 768,210, filed Oct. 8, 1968, now abandoned.

This invention relates to filters for tobacco smoke and is more particularly, but not exclusively, concerned with the production of an improved filter construction which may be used either as a filter tip for a cigarette or as a filter in a cigarette holder.

It is known that the smoke derived from tobacco is very complex and includes a substantial solid content as well as gases. The solid content, which comprises tar, carbon and other matter including nicotine, is commonly referred to as total particulate matters (T.P.M.) and is considered to be the main source of substances which are injurious to the health of the smoker.

The gases in tobacco smoke include as the main constituents the usual products of combustion, carbon dioxide and water vapor, but they also include toxic gases, acetic acid, hydrogen sulphide and ammonium gases and sometimes hydrocyanic acid and carbonmonoxide, all of which are considered as being harmful to the smoker. These harmful gases are present in varying proportions according to the kind or quality of tobacco and they impart an acid property to the tobacco smoke stream, because the ammonium gases, which are the only basic gases, are present in very small quantities. In fact the smoke from the tobacco which includes gases and the T.P.M. is characterized as being acidic.

Many attempts have been made to clean tobacco smoke without affecting the aroma or taste of the smoke, and in particular to remove the total particulate matters. These attempts have been based on the concept of a physical filtration of the tobacco smoke, but they have not been more than very partially successful.

The present invention is concerned with a novel filter which will prove very much more effective than the filters previously employed.

The present invention provides a filter which contains a solid chemical substance which is non-toxic, which has an alkaline characteristic property, and which is efiective to react chemically with constituents of the tobacco smoke to facilitate removal of harmful constituents from the tobacco smoke during its passage through the filter.

The present invention further provides a filter which includes a solid non-toxic chemical substance with an alkaline characteristic and capable of reacting with acid constituents of the tobacco smoke to form water in the filter, whereby the filtration of the tobacco smoke to remove harmful constituents is facilitated by the passage of the smoke through water in the filter.

It will thus be seen that the filtering action in accordance with the present invention is based principally on the concept of a chemical change taking place during the passage of the tobacco smoke through the filter. The previously used filters for tobacco smoke have been based on a physical action in which the smoke is drawn through an arrangement of obstacles upon which particulate matter becomes deposited, without any action at all taking place on the injurious acids.

However, the filter in accordance with the present invention is partly chemical and partly physical in its mode of action, The chemical reaction with the acid constituents of the tobacco smoke is itself efiective to remove harmful constituents from the smoke, and a physical filtration through water formed in the chemical reaction enhances the filtration ir respective of whether conventional filter parts for tobacco smoke are also present or not.

Advantageously the solid chemical substance which is used in the filter in accordance with the present invention is incorporated between conventional filter parts so that the improved filtration of the present invention is additional to a conventional physical filtration.

A filter for tobacco smoke in accordance with the present invention preferably includes a non-toxic hydroxide of an element of group 11A of the periodic table of Mendeleef, which hydroxide is capable of reacting with the acid gases present in tobacco smoke at the temperature at which the tobacco smoke is inhaled by the smoker. Calcium hydroxide is the chemical substance which is preferred in accordance with the present invention, but it is possible that either magnesium hydroxide or strontium hydroxide may be used as alternatives, although both these substances are very much more expensive than calcium hydroxide and not so efficient in their filtering action as calcium hydroxide.

It has been found that the efficiency of the filter in accordance with the present invention increases with the selection of particular granular sizes of the chemical substance employed, and the very best results which have been obtained so far in accordance with the present invention have been obtained using calcium hydroxide particles of a size which will pass through a 60 A.S.T.M. mesh sieve and are retained on an A.S.T.M. mesh sieve.

Further in accordance with the present invention the preferred chemical substance for inclusion in the filter, that is to say the calcium hydroxide of the above stated range of particle size, is obtained by taking pure white marble, which is a pure crystalline compacted calcium carbonate and which is obtainable as such in nature, and heating it gradually over a period of four to five hours from room temperature to a temperature of l,000 C., at which temperature the substance is maintained for 1 hour. Preferably the heating is carried out in an electric furnace. The resulting pure calcium oxide is cooled to normal temperature in a desiccator and is then mixed with a small amount of water sufficient to make a paste and is then dried at C. for about 1 hour. The material which is obtained after drying the paste is a specially treated form of slaked calcium hydroxide and this material, which is a white amorphous powder, is passed through fraction sieves to select those particles which lie within the range of particle size 60 mesh sieve to 80 mesh sieve according to the A.S.T.M. Standard.

The quantity of the specially treated slaked calcium hydroxide which is included in the filter will depend on the tobacco which is being smoked. The operation of the filter will now be described, and it will be realized that it is contemplated that the chemical substance, preferably slaked calcium hydroxide of the stated range of particle size, may be included between conventional filter parts even though no mention of the conventional filter parts is made in the ensuing description. in the preferred embodiment of the invention there is provided a filter for filtering tobacco smoke which contains at least one filter charge having a cross-sectional dimension corresponding to that of a tobacco smoke passage wherein the charge consists essentially of calcium hydroxide particles wherein the calcium hydroxide has a particle size such that the particles are retained on an 80 A.S.T.M. mesh sieve and will pass through a 60 A.S.T.M. mesh sieve, wherein the particles are in contact with each other in sufficient amount to receive a major portion of the total particulate matter as a result of the passage of the smoke between the particles and through the water of reaction formed on and located between the particles.

The tobacco smoke which is drawn through the filter is carrying total particulate matters by reason of the velocity of the gas which is dependent upon the suction effect induced by the smoker and by reason of the overall density of the tobacco smoke which enables the total particulate matters to be suspended in and carried by the tobacco smoke. When the passage of the smoke through the filter is impeded by the slaked calcium hydroxide, the velocity of the tobacco smoke is reduced and a first deposition of total particulate matters occurs.

However, the tobacco smoke contains water vapor, and in the presence of this water vapor the calcium hydroxide particles of the filter react with the acid gases also present in the tobacco smoke. The reaction is the standard reaction of an acid and a base which yields the calcium salt of the acid and water.

The water which is formed in the chemical reaction accumulates in the filter as a liquid layer formed on the particles of calcium hydroxide themselves, and consequently the tobacco smoke which passes through the filter has to pass through this liquid layer. It is found that the tobacco smoke which has passed through the liquid layer of water is a mild, fresh and pleasant smoke which is inhaled by the smoker.

During the passage of the tobacco smoke through the water layer on the particles of calcium hydroxide comprising the filter, compounds, such as ammonia and nicotine, become partially dissolved in the water. The quantity of water present is comparatively small and therefore the quantity of the nicotine and ammonia dissolved is also small, but as these compounds form a very small proportion of the total content of the tobacco smoke there is an effective removal of these compounds by the dissolving in the water which is chemically produced in the filter.

It will therefore be understood that the acid gases, i.e., acetic acid, hydrogen sulphide, etc., are removed from the tobacco smoke by chemical reaction in the filter of this invention, and the ammonium gases are removed by being dissolved. These gases are some of the denser gases comprising the tobacco smoke, and when these gases have been removed the density of the tobacco smoke has been reduced by a substantial amount. The decrease in density of the tobacco smoke which takes place is a decrease from a density capable of carrying total particulate matters to a level of density which is not capable of carrying the total particulate matters. Consequently sedimentation takes place in the filter with the deposit of a very large proportion of the total particulate matters.

In addition to the chemical reaction and the sedimentation consequent upon reductions in the velocity and density of the tobacco smoke, the action of drawing the tobacco smoke through the water layer formed in the filter has a physical filtration effect on the total particulate matters. There is a kind of surface cohesion effect which retains the total particulate matters in the water formed in the filter, that is to say on the particles of calcium hydroxide.

It is found that a filter including calcium hydroxide prepared as described above removes a very high percentage (in some cases as much as 90 percent) of the total particulate matters, the harmful gases and nicotine from the tobacco smoke without affecting the aroma and taste of the tobacco smoke. it is also found that tobacco smoke which has passed through a filter in accordance with this invention has had its acidity very substantially reduced, as confirmed by tests with the various indicators such as methyl red, methyl orange, etc., thus showing that acid constituents of the original smoke have been very largely removed.

Experiments have shown that as the particle size of the calcium hydroxide particles used in the filter of the present invention are decreased towards the preferred range of particle size from 60 A.S.T.M. mesh sieve to A.S.T.M. mesh sieve so the efficiency of the filter increases. However, if the particle size of the calcium hydroxide is further decreased to include particles which will pass through an 80 A.S.T.M. mesh sieve the filter tends to clog and is not nearly so satisfactory.

It will be understood that according to one aspect the present invention provides a method of filtering tobacco smoke by causing the main stream of gases comprising the tobacco smoke, which are acidic in nature and which contain water vapor, to come in contact with a non-toxic alkaline substance in granular form and to react therewith to produce neutral substances and water, which water forms a sheath on the granules and acts to dissolve other compounds present in the tobacco smoke, whereby the density of the gaseous components of the tobacco smoke is reduced sufficiently to cause total particulate matters in the tobacco smoke to be substantially deposited in the filter on the said alkaline substance.

While it is preferred for a filter in accordance with the invention to be incorporated in a cigarette holder, it is equally within the ambit of the invention for the filter to be incorporated as part of a filter tip of a cigarette.

We claim: 1. A filter for filtering tobacco smoke which contains at least one filter charge having a cross-sectional dimension corresponding to that of a tobacco smoke passage, said charge consisting essentially of calcium hydroxide particles wherein the calcium hydroxide has a particle size such that the particles are retained on an 80 A.S.T.M. mesh sieve and will pass through a 60 A.S.T.M. mesh sieve said particles being in contact with each other and being in sufficient amount to remove a major portion of the total particulate matter as a result of the passage of the smoke between said particles and through the water of reaction formed on and located between said particles.

2. A cigarette containing the filter of claim 1.

3. A cigarette holder containing the filter of claim 1.

"H050 I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 669; 126 Dated June 13, 1972 Elie Michel Soussa and Jabbour Habayeb I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The full name of Jabbour Habayeb, co-rinventor in the above-identified patent is Jabbour Salim Habayeb.

Signedand sealed this 17th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOT'I'SCHALK v Qommissionerof Patents Attesting Officer 

2. A cigarette containing the filter of claim
 1. 3. A cigarette holder containing the filter of claim
 1. 